Hungary's sole nuclear power plant will be shut down next week because of low water levels in the river Danube, Prime Minister Peter Magyar said Friday as central Europe slogs through the latest in a series of heatwaves. The nuclear plant in Paks, south of Budapest, provides around 40 percent of Hungary's annual electricity generation. The operator of the plant, whose four reactors built with Soviet-era technology are cooled by water pumped from the Danube, warned earlier that a shutdown was "unavoidable". The Danube has dropped to record low levels in some parts because of prolonged rain shortages and successive heatwaves since May. Romania has already shut one of its nuclear reactors for the same reason and has announced it would close the second.